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How long does it take the contraceptive pill to work?

A lot of women still prefer the contraceptive pill as a non-invasive option for preventing pregnancy these days. If you have decided to use the pill, you may be wondering when exactly it will start protecting you from becoming pregnant.

While there is a general guide as to when you can expect the pill to take effect, there are other factors that will affect how long it will take the pill to start working. But first, let’s briefly look at what the pill contains, how it actually works and how to take it, depending on which type you choose to use.

What’s in the contraceptive pill?

The contraceptive pill is an oral form of contraception which is available as either the combined pill or mini pill, also known as progesterone only pill (POP). They both contain hormones which your body produces naturally. The combined pill contains two hormones which are oestrogen and progesterone, and is popular among women under 35 years old. The mini pill contains only progesterone and is mainly offered to women who are above 35 years or women who are breastfeeding.

How does the contraceptive pill work?

The three main ways the pill works to prevent pregnancy are:

  • It prevents ovulation (the release of an egg from your ovary) each month
  • It thins the lining of your womb, making it harder for a fertilised egg to attach to your womb and start growing
  • It thickens the mucus lining the cervix of your womb, making it difficult for sperm to swim through and fertilise your egg

Female taking the pillHow to take the contraceptive pill

It is important to follow the instructions in your specific pill pack if you want it to work effectively, and as soon as possible. Remember to tell your GP about any other medicines you are taking or any medical conditions you have, as these issues may affect how well the pill will work for you. 

The combined pill should be taken continuously for 21 days after which you should have a 7-day pill free break, during which you should have a breakthrough period. You will then continue with your pills for another 21 days, even if you are still having your breakthrough period. You should also remember to take the pill around the same time every day until the pack is finished.

If you are using the mini pill, you should take the pill every day without any breaks. Your pills may come as 28 day or 35 day packs, and there will be specific instructions with them about how and when you should take the pill each day. With the mini pill, it is important to remember that there are no breaks between packs, so when you finish one pack, you should start a new one the next day.

When will the contraceptive pill start working?

Generally, the pill should begin working 7 days after you start taking it, without the need for you to use another contraception like condoms. However, condoms should still be used to be protected against STIs.

There are a few points to note about how long it takes for the pill to begin working, below:

  • The day in your menstrual cycle you begin taking the pill will determine when it starts to work.

  • If you begin taking either the combined pill or mini pill on day 1 to 5 of your period, you will be protected straight away from getting pregnant without the need for additional contraception.

  • If you have a short menstrual period that is 23 days or fewer every month, you will need to use alternative contraceptive methods (for example condoms) as well, to prevent pregnancy. For the combined pill, you will need to use additional contraception for the first 7 days of taking the pill and for the mini pill, the first 2 days.

  • If you begin using the pill on any other day outside day 1 to 5 of your menstrual cycle, you will not be protected from pregnancy immediately. In such cases, for the combined pill or the mini pill, you should use another contraception such as condoms in addition to the pill. This will be for the first 7 days for the combined pill, or the first 2 days for the mini pill.

  • If you just had a baby and are not breastfeeding, you can start the combined pill on the 21st day after giving birth. If you start the pill after 21 days, you will also need another form of contraception for the first 7 days, before the pill will begin working on its own.

  • If you are a breastfeeding mother, the mini pill is the preferred birth control option and should be started on day 21 after having your baby. If you start the mini pill 21 days after giving birth, you will also need other contraceptive methods like condoms for the first 2 days, after which it will take effect on its own.

  • If you just had an abortion or a miscarriage, you can start the pill within the first 5 days and it will begin working immediately. If you wait for more than 5 days afterwards to start the pill, you will need to use another form of contraception such as condoms for the first 7 days (for the combined pill), or the first 2 days (for the mini pill) before they will be effective on their own.

If you are ever unsure about how to use your contraceptive pills or if you miss a pill, you should always speak to your GP who will provide further information and advise you on what to do next.



Authored & Reviewed By

Mohamed Imran Lakhi

MPharm - Lead Pharmacist
Imran Lakhi is the superintendent pharmacist and founder at Prescription Doctor. He has been at the core of our team.

Published on: 06/09/2019 Reviewed on: 18/05/2023
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